Optical relay systems of this kind are used e.g. in endoscopes or similar optical devices. A relay system images the object F1, generated by an objective lens into the image F2. Endoscopes comprise also several relay systems, mounted one after the other and generating a last intermediate image in the focal plane of the ocular lens or, with or without an additional lens, on a detector, e.g. film or CCD.
Relay systems of this kind are known. FIG. 1 shows a simple example, wherein all image aberrations may be corrected. However, this system has a very pronounced vignetting making it almost unusable for film and television applications. Another known system, shown in FIG. 2, allows to eliminate the vignetting but does not allow to correct the image field. The aberrations multiply with the number of relay systems mounted in the optical device. This problem is solved in the state of the art with compensating objective and/or ocular lenses. With such lenses, however, a different objective or ocular must be used each time, the number of relay systems is changed in order to vary the overall length or the image orientation. A further disadvantage lies in the fact that the uncorrected separations demand narrow tolerances and that the possibility of compensating such an objective lens implies a given limit for the number of relay systems.
Further, relay systems are known, e.g. according to German DE 2,619,393-C2 or German DE 3,534,210-A1, wherein the image field may be corrected and the vignetting may be eliminated. A disadvantage of these systems is, however, that they comprise uncemented lenses with large focal distances which are difficult to center and consequently of elevated cost. They also require a very precise mounting.
The principal object of the present invention is to design a relay lens system, wherein all image aberrations may be corrected, which therefore permits modular use, and which has no stand-alone lenses or lenses with great focal distance.